Wound treatment apparatus including a heater and an IR-transparent of IR-transmissive bandage

ABSTRACT

A wound treatment apparatus is provided which includes a bandage that is transparent to, or transmissive of, energy in the infrared (IR) range of the electromagnetic spectrum, a heater that generates heat, and an attachment device for retaining the heater over or on the bandage. The bandage and heater together have a low profile so as to be convenient for a patient, and are flexible so as to conform to the shape of a wound and to contours of the skin near the wound. The bandage is provided with an adhesive pattern for maintaining moisture at the wound site. The heater may maintain a normothermic condition at the wound treatment area. A controller may be provided for cycling the temperature of the heater in order to maintain the normothermic condition.

CROSS-REFERENCES TO RELATED PATENT AND COPENDING APPLICATIONS

This application is a Continuation of U.S. Ser. No. 09/566,969, filedMay 9, 2000 now U.S. Pat. No. 6,440,156, which is a Continuation of U.S.Ser. No. 09/056,063, filed Apr. 6, 1998 now U.S. Pat. No. 6,080,189,from which it claims priority. This application also contains materialrelated to the following commonly assigned pending U.S. PatentApplications:

Ser. No. 07/900,656, filed Jun. 19, 1992, for “THERMAL BODY TREATMENTAPPARATUS AND METHOD”, now abandoned;

Ser. No. 08/342,741, filed Nov. 21, 1994, for WOUND TREATMENT DEVICE”,now U.S. Pat. No. 5,817,145, now abandoned;

Ser. No. 08/356,325, filed Feb. 21, 1995, for “WOUND COVERING”, nowabandoned;

Ser. No. 08/785,794, filed Jan. 21, 1997, for “NORMOTHERMIC HEATER WOUNDCOVERING”, now U.S. Pat. No. 5,986,163, issued Nov. 16, 1999;

Ser. No. 08/786,713, filed Jan. 21, 1997, for “NORMOTHERMIC TISSUEHEATING WOUND COVERING”, now U.S. Pat. No. 5,954,689, issued Sep. 21,1999;

Ser. No. 08/786,714, filed Jan. 21, 1997, for “NEAR HYPOTHERMIC HEATERWOUND COVERING”, now U.S. Pat. No. 5,954,680, issued Sep. 21, 1999;

Ser. No. 08/838,618, filed Apr. 11, 1997, for “FLEXIBLE NON-CONTACTWOUND TREATMENT DEVICE”, now U.S. Pat. No. 6,093,160, issued Jul. 25,2000;

Ser. No. 08/843,072 filed on Apr. 11, 1997 entitled “FLEXIBLENON-CONTACT WOUND TREATMENT DEVICE WITH A SINGLE JOINT, now U.S. Pat.No. 6,110,197, issued Aug. 29, 2000”;

Ser. No. 09/056,191 filed Apr. 6, 1998 for “WOUND TREATMENT APPARATUSWITH A HEATER, A HEAT CONDUCTIVE BANDAGE, AND A HEAT-SPREADING MEANSACTING BETWEEN THE HEATER AND BANDAGE”, now U.S. Pat. No. 6,235,047,issued May 22, 2001;

Ser. No. 09/055,725 filed Apr. 6, 1998 for “WOUND TREATMENT APPARATUSWITH INFRARED ABSORPTIVE WOUND COVER”, now U.S. Pat. No. 6,213,965,issued Apr. 10, 2001;

Ser. No. 09/055,597 filed Apr. 6, 1998 for “WOUND TREATMENT APPARATUSWITH A HEATER ADHESIVELY JOINED TO A BANDAGE”, now U.S. Pat. No.6,071,304 issued Jun. 6, 2000; and,

Ser. No. 09/055,605 filed Apr. 6, 1998 for “WOUND TREATMENT APPARATUSFOR NORMOTHERMIC TREATMENT OF WOUNDS”, now U.S. Pat. No. 6,095,992,issued Aug. 1, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a wound treatment device with a bandagethat is essentially transparent in the infrared range of theelectro-magnetic spectrum and a heater that emits energy in the IRrange. The bandage and heater are connected or joined by an attachmentmeans that holds the heater in position on or over the bandage.

2. Description of the Related Art

Wounds, in general, are breaks in the integrity of the skin of apatient. A first type of wound may result from mechanical trauma thatproduces a cut, tear, or an abrasion. There are many instruments ofcausality for such wounds, including knives, glass, gravel, or ascalpel. A second type of wound may be caused by a combination of heatand pressure wherein the heat alone is insufficient to cause an outrightburn. Such wounds include pressure sores, decubitus ulcers, or bedsores, and reflect an injury that is chronic in nature. A wound may alsobe vascular in origin. In this third type of wound, blood flow through aregion may be altered sufficiently to cause secondary weakening oftissues which are eventually disrupted, thus forming a wound. In thecase of arterial causes, the primary difficulty is getting oxygenatedblood to the affected area. For venous causes, the primary difficulty isfluid congestion in the affected area which backs up, decreasing theflow of oxygenated blood. Because these wounds manifest underlyingchronic disease processes, such as atherosclerotic vascular disease,congestive heart failure, and diabetes, these vascular injuries also arechronic in nature, forming wounds with ulcerated bases.

Heat therapy has been used to treat wounds since the days ofHippocrates, with varying results. Up to now, heat therapy for woundshas involved the application of heat under conditions that make thetissues of a wound hyperthermic. Hyperthermia impedes wound healing andmay actually damage the wound tissues.

The “normal” range of temperature for the human body is 37° C.±1° C.(36° C.-38° C.). This is termed the “normothermic” range. Humans exhibita thermoregulatory response to core temperature changes as little as±0.1° C., wherein “core” as used herein refers to interior portions ofthe body. This extremely tight temperature control is necessary becausevirtually all cellular functions, chemical reactions and enzymaticreactions are optimum at normothermia.

Surface tissue varies in temperature according to where on the body itis located. The skin of the torso is usually hypothermic, while the skinof the legs is always hypothernic. The normal skin temperature of thedistal leg is approximately 32° C., which is considered to be“moderately hypothermic”. The skin temperature of the distal leg of apatient with vascular insufficiency may be as low as 25° C., which is“severely hypothermic”. The hypothermic condition of wounds and ulcersinhibits healing. Severely hypothermic skin or wound tissue is in astate that may be termed “suspended animation”. In suspended animation,tissue is living, but cellular functions necessary for cell division andcollagen deposition are slowed or even stopped. Further, the immunesystem is inhibited, allowing wounds to become heavily colonized withbacteria. The local application of heat to hypothermic skin will causesome degree of vasodilatation, resulting in an increase in local bloodflow. Increased blood flow increases the subcutaneous oxygen tension(PsqO₂) which, in turn, increases both collagen deposition and immunefunction.

Many references report that the immune system is inhibited byhypothermia and activated by mild hyperthermia (fever). Persp Biol Med:439-474, Spring 1980, reports that local body temperature is a criticalfactor determining host susceptibility, the location of lesions andcontracting infectious diseases. New Eng J Med 305:808-814, 1981,reports that animals exposed to cold environments are more susceptibleto infectious diseases, whereas exposure to high ambient temperaturesoften produces a beneficial result. Wound Rep Reg 2:48-56, 1994 and ActaAnaesth Scand 38:201-205, 1994, report that infections caused by astandard inoculum of e. coli or s. aureus were significantly more severein hypothermic guinea pigs than in normothermic control animals. New EngJ Med 334:1209-1215, 1996, reports that hypothermic colorectal surgicalpatients had three times more wound infections (19% vs. 6%) than thosewho were kept normothermic during surgery with a Bair Hugger® patientwarming system described in commonly assigned U.S. Pat. Nos. 5,324,320,5,300,102 and 5,350,417. Further, six weeks of warming therapy with theBair Hugger® patient warming system has successfully healed chronicprogressive ulcers which heretofore have been resistant to standardtherapies.

Currently available medical devices that apply heat to wounds includeinfrared lights, warm water pads, warm water bottles, whirlpools andSitz baths. All types of lesions, such as surgical, chronic, traumatic,donor sites, infected wounds and burns, have been treated with thesewarming modalities. Particularly difficult has been the application ofheat to open wounds such as ulcers. Treatment of a wound with infraredlight requires that the wound be positioned under the light duringtherapy, necessitating patient immobility. Further, the infrared heatcauses the wound to dry, thereby slowing the healing process. Warm waterpads and bottles and electrical heating pads are cumbersome, reducepatient mobility, and are usually applied to the extremities and held inplace with inconvenient wraps such as straps, hook-and-eye material ortabs. Whirlpools and Sitz baths reduce mobility and limit the durationof warming therapy due to skin maceration by the water. None of thesemodalities is capable of prolonged heat treatment of a wound.

SUMMARY OF THE INVENTION

There is a need for a wound treatment apparatus to treat a wound withheat for a prolonged period of time, while promoting patient convenienceand mobility. Preferably, the treatment would produce a substantiallynormothermic condition at the wound. It Is also important that the woundtreatment apparatus be flexible and have a low profile for convenienceof the patient. Such a wound treatment apparatus should efficientlytransfer heat to a treatment site, be convenient to operate withoutadversely impacting the patient, and be capable of maintaining a moistwound environment.

Preferably, the placement of the wound treatment apparatus is referredto a “wound treatment area” (or “treatment area”) that may include thewound, unwounded skin adjacent the wound (the periwound), or both.

The invention is a wound treatment apparatus that includes three parts.First is a wound bandage that is transparent or at least transmissive inthe infrared (IR) range of the electromagnetic spectrum. The second partis a heater that is disposed on or over the bandage. The heater emits asignificant amount of its energy in the IR range. The third part of theinvention is an attachment means to hold the heater in position over thebandage.

Other objects and advantages of the invention will become apparent uponreading the following description taken together with the accompanyingdrawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a first embodiment of the wound treatmentapparatus being applied to a wound on a person's body;

FIG. 2 is an isometric view of the wound treatment apparatus applied tothe wound on the person's body; and

FIG. 3 is an exploded isometric view of the wound treatment apparatus;

FIG. 4 is a cross-sectional view of the wound treatment apparatusapplied to the wound on the person's body;

FIG. 5 is a plan view of a second surface of a wound treatment apparatusbandage;

FIG. 6A is a planar illustration of an electrical resistance elementembedded in a flexible layer for uniform heating;

FIG. 6B is a view taken along plane VIB of VIB FIG. 6A;

FIG. 7A is a planar view of an electrical resistance element embedded ina flexible layer for heating a portion of a treatment area;

FIG. 7B is a view taken along plane VIIB—VIIB of FIG. 7A;

FIG. 8A is a planar view of an electrical resistance element embedded ina flexible layer for uniform heating of a central portion of a treatmentarea; and

FIG. 8B is a view taken along plane VIIIB—VIIIB of FIG. 8A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures, wherein like reference numerals designatelike or similar parts throughout the several views there are shownvarious embodiments of a wound treatment apparatus in according to thisinvention.

As shown in FIGS. 1-5, the wound treatment apparatus 100 includes abandage 102 fabricated from a material that is transparent to or atleast transmissive of energy in the IR range. The bandage 102 has first(lower) and second (upper) surfaces 104 and 106. A heater 108 generatesthermal energy and emits a significant amount of this energy in the IRrange. The heater 108 includes first (lower) and second (upper) surfaces110 and 112. An attachment means holds the heater 108 in position overthe bandage 102 in such a manner as to transfer heat from the heater 108through the bandage 102. The attachment means may maintain the secondsurface 106 of the bandage 102 and the first surface 110 of the heater108 in full, or partial, contact, or out of contact. In FIGS. 2 and 4,the wound treatment apparatus 100 is shown in place covering a wound 116of a person's body 118. Immediately adjacent the wound is a periwoundarea 120 which is typically a peripheral band of tissue around thetissue of the wound area with less trauma than the wound area. The woundtreatment apparatus 100 is capable of treating a wound treatment areathat includes the wound and/or the periwound area, as desired.

In the wound treatment apparatus 100, the heater 108 includes means forgenerating heat that may be electrically operated. For example, themeans may take the form of an electrical resistance element 124 embeddedin or laminated to a planar member of flexible material 126, such aspolyethylene, silicon, rubber or flexible cloth. In this regard, theheater 108 would form a “black body” that radiates heat in the form ofenergy in the IR range. In the preferred embodiment, the heater 108 issubstantially planar, as shown in FIGS. 1 and 3, and yet flexible inorder that it might conform, with the bandage 102, to the wound 116, asshown in FIG. 4, and to the person's body, as shown in FIGS. 2 and 4.

As illustrated in FIGS. 1 and 2, the electrical resistance element 124is connected to first and second electrical conductors 128 and 130,which are connected to an electrical power source 132, via a controller134. The purpose of the controller 134 is to control electrical powerprovided to the electrical resistance element 124. In this regard, theoperation of the heater 108 may be cycled by the controller to maintainthe tissue in the wound treatment area at a normothermic or a nearnormothermic temperature. As shown in FIGS. 1 and 2, the electricalresistance element 124 may extend back and forth in the flexible planarmember 126 with a desired spacing to promote uniform heating of theheater 108.

As shown in FIG. 5, the first surface 104 of the bandage 102 is providedwith an pattern of adhesive 136 adjacent its periphery. The adhesivepattern 136 may completely encompass the wound and the periwound areasso as to trap the natural moisture of the body which, in turn, maintainsa moist environment across the wound treatment area for wound therapypurposes. Accordingly, the pattern of adhesive 136 has inner and outerboundaries 138 and 140 wherein, in the preferred embodiment, the outerboundary 140 coincides with the outer perimeter of the bandage 102. Itshould be understood that the bandage 102, the heater 108, and thepattern of adhesive 136 may take various shapes, such as the squareshown in the drawings, or a rectangle, circle or ellipse, or any otherregular or irregular shape, depending upon various shapes of woundtreatment areas.

The bandage 102 is a flexible, planar member that is fabricated from amaterial that is substantially transparent to or transmissive of energyin the IR range. The bandage 102 is preferably made from a thin,uncoated, transparent polymeric film. For example, the bandage may beabout 5 mils, or less, in thickness. Examples of polymeric film materialwhich, when uncoated, are transparent to or transmit in the IR rangeinclude, without limitation: polyurethane, polyethylene, polypropylene,and polyvinyl chloride. Preferably, these materials are uniform inthickness so they cause little or no distortion of the infraredradiation thus providing a uniform transfer of energy. The bandage 102is uncoated on either surface 104 and 106, except for the adhesivepattern 136. Relatedly, the adhesive pattern 136 may comprise any shapeor pattern that adheres the first surface 104 of the bandage 102 to apatient's skin, maintains a moist environment at the wound treatmentarea, and leaves a large portion of the first surface 104 unobstructedso that IR energy may pass therethrough to the wound treatment area.Since human body tissue comprises a large amount of water, the IR energygenerated by the heater 108 and transmitted through the bandage 102 willbe absorbed by the tissue in and near the wound treatment area, therebywarming the tissue. Manifestly, the structure of the wound treatmentapparatus 100 as thus far described maintains a closed, moist, heatedenvironment at and over the wound treatment area to promote fast healingof wounded tissue.

FIGS. 6-8 illustrate various embodiments of electrical resistanceelements for the heater 108. In the heater 108 a shown in FIG. 6A, anelectrical resistance element 124 a winds back and forth within theflexible planar member 126, similar to what is shown in FIG. 1. Thespacing between the windings of the electrical resistance element 124 amay be sized so as to ensure substantially uniform heating of the heater108 a. FIG. 6B shows the electrical resistance element embedded orlaminated in the flexible planar member 126. In FIG. 7A, the electricalresistance element 124 b takes a path along a peripheral zone of theflexible planar member 126, so that the periphery of the heater 108 b isuniformly heated to a temperature greater than a central portion of theheater. Again, these electrical resistance elements 124 b are shownembedded or laminated in the flexible planar member 126 in FIG. 7A. InFIG. 8A, the electrical resistance element 124 c takes a spiral path outand back within a central region of the heater 108 c so as to uniformlyheat the central region of the heater to a higher temperature thanregions outbound therefrom The heater 108 a is adapted for applying heatto both the wound and periwound area 116 and 120 in FIG. 4, the heater108 b is adapted for applying heat primarily to the periwound area 120and the heater 108 c is adapted for applying heat primarily to the wound116.

Although the means in the heater 108 for generating heat is disclosedand described above as being electrically-actuated, this is not intendedto limit the heater 108 solely to electrical operation. In fact, otherheat generating means that would be suitable for the heater 108 include,without limitation, chemical heaters, water pad heaters, andphase-change salt heaters. Chemical heaters and phase-change saltheaters would preferably be formed into a relatively thin pad and sealedin a pouch made of polymeric film. A water pad heater can be fabricatedby thermo-forming two sheets of polymeric film into fluid channels andsealing the sheets at their peripheries. Warm water is then circulatedthrough the pad from an external source of hot water.

Many surfaces of the body have convexities and concavities in closeproximity to one another. See for example the profile of the person'sbody 118 in the vicinity of the wound 116 in FIG. 4. The bandage 102, inbeing transparent to or transmissive of energy in the IR region, isimportant because of the difficulty in achieving a continuous, uniformthermal contact for conductive heat transfer between the upper surface106 of the bandage 102 and the first surface 110 of the heater 108, evenwhen the heater 108 is fabricated to be moderately flexible andsubstantially planar. Even a highly flexible planar heater will tend torest on top of the convexities and not touch the bottom of theconcavities. For example, consider the profile of an ulcer on the skin.Consider further that base of the ulcer is sharply recessed. In thiscase, the base of the ulcer may not even be contacted by the firstsurface 104 of the bandage 102.

The invention contemplates that the first surface 110 of the heater 108may be in full, or partial contact with the second surface 106 of thebandage 102. In the areas where the first surface 110 and the secondsurface 106 are in contact, heat will be transferred by conductionbetween the first surface 110 and the second surface 106. However, itmay be very difficult to conform even the most flexible, substantiallyplanar configuration of the heater 108 to the contours of the humanbody, and further to the contours of any particular wound. Therefore, inmany cases, areas of non-contact between the heater 108 and the secondsurface 106 will exist, creating air spaces which act as pockets ofthermal insulation.

In prior art heater/bandage combinations only inefficient convectiveheat transfer occurs in air spaces because the bandages are nottransparent in the IR region. The areas of contact (supportingconductive heat transfer) and the areas of non-contact (supportingconvective heat transfer) may have large and unpredictable differencesin temperature and heat transfer, resulting in substantialnon-uniformities in distribution of the heat across the prior artbandages. The result is that, with prior art heater/bandagecombinations, heating of the wound treatment area may be uneven,unpredictable, and ineffective in treating a wound.

With the bandage 102 being fabricated from material that is transparentto or transmissive of energy in the IR range, and with the heater 108acting as a radiating black body, a significant component of heat istransferred to, and through, the bandage 102 by radiation. Therefore, inthe areas where the first surface 110 of the heater 108 does not contactthe second surface 106 of the bandage 102, significant amounts of heatwill be transferred by radiation. The invention therefore overcomes theinherent unevenness of heat transfer to the wound treatment area in theprior art heater/bandage combinations where heat transfer from heater tobandage is by conduction and convection only. In this invention, heattransfer between the heater 108 and the bandage 102 is by conduction,convection, and radiation. This provides more efficient, and moreuniform, heat transfer from the heater 108 to the bandage 102. Thiscreates a more uniform distribution of heat in, and through, the bandage102, providing a more even distribution of heat across the tissue in andnear the wound treatment area.

This invention further improves on the prior art modes of heating awound with IR energy as, for example, where wounds are exposed to theoutput of high temperature heat lamps. In these case, the heat lampsshine on open, exposed wound treatment areas, causing drying of woundtissue, which inhibits and delays healing. This invention interposes anIR transparent (or transmissive) film bandage layer between the IR heatsource and the wound which seals about the wound, retaining moisture atthe wound and preventing its drying.

The third component of this invention is an attachment means to hold theheater 108 in position on, or over, the bandage 102. Such means mayinclude, for example, a pattern of adhesive that acts between the firstsurface 110 of the heater 108 and the second surface 106 of the bandage102. The pattern may have, for example, the shape and composition of thepattern illustrated in FIG. 5. This pattern of adhesive may be on thesecond surface 106 of the bandage 102 or on the first surface 100 of theheater 108. Alternatively, it may comprise a separate film of two-sidedadhesive between the surfaces 106 and 110. Other attachment meanscontemplated for use in this invention include, without limitation,hook-and-eye material, a pocket formed on the second surface 106 of thebandage 102, tabs, tapes, straps, clamps, and so forth. The function ofthe attachment means is to hold the heater 108 in close proximity to thebandage 102. The function may result in full or partial contact betweenthe first surface 110 of the heater 108 and the second surface 106 ofthe bandage 102, or may even result in the heater 108 being heldslightly off of the second surface 106, out of direct contact with thebandage 102.

Clearly, other embodiments and modifications of this invention willoccur readily to those of ordinary skill in the art in view of theseteachings. Therefore, this invention is to be limited only by thefollowing claims, which include all such embodiments and modificationswhen viewed in conjunction with the above specification and accompanyingdrawings.

We claim:
 1. A treatment device comprising: a bandage having first andsecond surfaces, the first surface of the bandage defining a treatmentarea; the bandage being substantially transparent to energy in theinfrared (IR) range of the electromagnetic spectrum; a heater for beingpositioned over the second surface of the bandage; and an attachmentmeans acting between the heater and the second surface for retaining theheater over the bandage's second surface.
 2. The treatment device ofclaim 1, further including means for adhering the first surface of thebandage to a person's skin.
 3. The treatment device of claim 2, whereinthe means for adhering include a pattern of adhesive material on thefirst surface of the bandage.
 4. The treatment device of claim 1, theheater being electrically active.
 5. The treatment device of claim 4,the attachment means being a pattern of adhesive.
 6. The treatmentdevice of claim 4, the attachment means being a film of two-sidedadhesive.
 7. The treatment device of claim 4, the attachment means beinghook-and-eye material.
 8. The treatment device of claim 4, theattachment means being a pocket formed on the second surface of thebandage.
 9. The treatment device of claim 4, the attachment means beingselected from the group including tabs, tapes, straps, and clamps. 10.The treatment device of claim 1, the heater being a chemical heater. 11.The treatment device of claim 10, the attachment means being a patternof adhesive.
 12. The treatment device of claim 10, the attachment meansbeing a film of two-sided adhesive.
 13. The treatment device of claim10, the attachment means being hook-and-eye material.
 14. The treatmentdevice of claim 10, the attachment means being a pocket formed on thesecond surface of the bandage.
 15. The treatment device of claim 10, theattachment means being selected from the group including tabs, tapes,straps, and clamps.
 16. The treatment device of claim 1, the heaterbeing a water pad.
 17. The treatment device of claim 16 the heaterincluding two sheets of polymeric film thermo-formed into fluidchannels, the sheets being sealed at their peripheries.
 18. Thetreatment device of claim 16, the attachment means being a pattern ofadhesive.
 19. The treatment device of claim 16, the attachment meansbeing a film of two-sided adhesive.
 20. The treatment device of claim16, the attachment means being hook-and-eye material.
 21. The treatmentdevice of claim 16, the attachment means being a pocket formed on thesecond surface of the bandage.
 22. The treatment device of claim 16, theattachment means being selected from the group including tabs, tapes,straps, and clamps.
 23. The treatment device of claim 1, the heaterbeing a phase-change salt heater.
 24. The treatment device of claim 23,the heater including a pad sealed in a pouch.
 25. The treatment deviceof claim 23, the attachment means being a pattern of adhesive.
 26. Thetreatment device of claim 23, attachment means being a film of two-sidedadhesive.
 27. The treatment device of claim 23, the attachment meansbeing hook-and-eye material.
 28. The treatment device of claim 23, theattachment means being a pocket formed on the second surface of thebandage.
 29. The treatment device of claim 23, the attachment meansbeing elected from the group including tabs, tapes, straps, and clamps.30. The treatment device of claim 1, the attachment means being apattern of adhesive.
 31. The treatment device of claim 1, the attachmentmeans being a film of two-sided adhesive.
 32. The treatment device ofclaim 1, the attachment means being hook-and-eye material.
 33. Thetreatment device of claim 1, the attachment means being a pocket formedon the second surface of the bandage.
 34. The treatment device of claim1, the attachment means being selected from the group including tabs,tapes, straps, and clamps.